Chemistry stoicheometry

Question

how many grams of MgCl2 can be made from the 164 grams of HCl

Answer 1

Since it can be seen from the chemical formulas that there is 1 mol of Cl per mole of HCl and 2 moles of Cl per mole of MgCl2, we must account for this difference when doing our math. In this problem we are assuming that there is excess Mg available and that the reaction goes to completion. We can set up our equation like so to get from grams of HCl to grams of MgCl2:

g of MgCl2 = (164 g HCl)(1 mol HCl/36.46 g HCl)(1 mol Cl/1 mol HCl)(1 mol MgCl2/2 mol Cl)(95.21 g MgCl2/1 mol MgCl2)

Canceling out our units so that our final unit is grams of MgCl2, we find our answer to be 214.1 g MgCl2.